With the development of technologies, the fingerprint identification technology has become a standard configuration of most smart phones. A fingerprint identification process includes: acquiring an original fingerprint image by using a fingerprint identification module, then performing feature point matching between the original fingerprint image and a registered fingerprint profile, and unlocking or performing an instruction and the like operations upon successful matching.
At present, fingerprint identification apparatuses on the market have poor hydrophobic and oleophobic properties, and thus the fingerprint identification effect is affected during use due to such factors as moisture, sweat or oil stains on the finger (which is hereinafter referred to as a wet finger). As such, the fingerprint identification accuracy and fingerprint identification speed of the fingerprint identification apparatuses in a use environment such as the wet finger or the like are lowered, or even the fingerprints fail to be identified.
FIG. 1 to FIG. 3 illustrates the fingerprint detection principle. FIG. 1 is a schematic principle diagram of fingerprint detection by a conventional fingerprint identification apparatus for a dry finger. FIG. 2 is a schematic principle diagram of fingerprint detection by the conventional fingerprint identification apparatus for a wet finger. FIG. 3 is a schematic diagram of a water drop angle/a sweat drop angle of fingerprint detection by the conventional fingerprint identification apparatus for a wet finger. A sensing chip of the fingerprint identification apparatus is formed of a matrix electrode plate. The electrode plate forms a capacitance with finger patterns. A capacitance CV of the ridge pattern on the finger to the electrode plate is different from a capacitance CR of the valley pattern on the finger to the electrode plate. The fingerprint image is recovered by detecting the values of the capacitances. However, when a wet finger is pressed on the surface of a coating, the valleys of the fingerprints is filled with the water, sweat or oil stains on the finger, and the water sweat or oil stains on the wet finger may be spread on the surface of the coating. Since the water drop angle/or the sweat drop angle is small, the contact area between the water, sweat or oil stains on the finger and the surface of the coating is relatively larger, and thus the affected sensing region is larger, such that the fingerprint image may not be clearly recovered or fails to be recovered. This affects the fingerprint identification accuracy and fingerprint identification speed of the finger.